A biometric authentication system including a plurality of clients as terminal devices to input biometric information and a server performing biometric authentication by matching biometric information input at the client and a enrolled template biometric information enrolled in advance is known. In this biometric authentication system, each of the plurality of clients has a enrolled template performs biometric authentication based on the enrolled template, when connection with the server is not available.
In the biometric authentication system described above, the biometric information has a characteristic that difference from the enrolled template becomes larger according to environment or the biological body's change over time. That is, due to the difference in biometric information input from the plurality of clients and the elapse of time from the enrollment of the template, the biometric information becomes more subject to discarding, and the authentication rate decreases although the person to be authenticated is the corresponding person. With respect to such a problem, a technique to update the enrolled template using accepted biometric information is known. In addition, a technique to perform grouping of a plurality of clients based on the setting environment, and to update the enrolled template for each group is known.
In the technique to update the enrolled template using accepted biometric information, the client adds a time stamp to accepted biometric information, and the server collects the biometric information with the added time stamp. In addition, the server sets the biometric information with the latest time stamp among collected biometric information, and transmits the biometric information to the client. According to this, the client and the server can use the latest enrolled template.
Meanwhile, in the technique to update the enrolled template for each group, the plurality of clients are subjected to grouping based on the setting environment, and the server manages the enrolled template for each group with respect to the biometric information of each of the registrants. In addition, when updating the enrolled template using the accepted biometric information, the server updates only the enrolled template of the group to which the client with the input of biometric information belongs to. Accordingly, the discarding of biometric information due to the difference in input environment may be reduced. Note that related art is described, for example, in Japanese Laid-open Patent Publication No. 9-198501 and Japanese Laid-open Patent Publication No. 2003-316746.
However, according to the technique to update the enrolled template using the accepted biometric information, there is a possibility that biometric information input under an input environment that is different from the input environment of biometric information used for the update of the enrolled template may be discarded. For example, in a biometric authentication system using the fingerprint as the biometric information, it is assumed that there is a client that inputs biometric information by a slide-type fingerprint sensor, and a client that inputs biometric information by a flat-type fingerprint sensor. In such a biometric authentication system, when the enrolled template is updated by biometric information input by a flat-type fingerprint sensor, the input system of biometric information input by a slide-type fingerprint sensor is different from the enrolled template even though the fingerprint is the same. Due to this difference in the input system, there is a possibility that a difference is generated between the enrolled information and the biometric information, and the biometric information is discarded.
Meanwhile, according to the technique to update the enrolled template for each group, in a case such as when the enrolled template is updated based on biometric information input only in a certain group, there is a possibility that the biometric information is not accepted when biometric authentication is performed in another group. As described above, since the biological body being the basis of biometric information changes over time, when managing the enrolled template for each group and biometric authentication is performed by a client of a group for which the enrolled template is not updated for a certain period, there is a possibility that biometric information is discarded because the enrolled template is old with respect to input biometric information.
As described above, the conventional technique to update the enrolled template using the accepted biometric information has a problem that the enrolled template is not updated to appropriate biometric information.